Free or cheap Swap meets/flea markets?

I’m looking to sell off a bunch of my stuff to pay for my dog’s surgery and finding a new place to live, but I have no idea where to go and do this. I’ve heard of swap meets or flea markets that used to just let you set up a blanket or a table and let you sell your stuff. Does anywhere in Seattle, Tacoma or nearby cities do this?

Any advice is helpful.